Why does my code generated from MATLAB Coder fail to compile because of missing function definitions for "omp_init_nest_lock" and "omp_destroy_nest_lock"?

Why does my code generated from MATLAB Coder fail to compile because of missing function definitions for "omp_init_nest_lock" and "omp_destroy_nest_lock"?

I am trying to compile the code on a Linux operating system and it fails because the compiler cannot find definitions for the mentioned functions. I do not know why these functions are appear in my code. I also noticed that the same code compiles on a different computer with a Windows operating system using Microsoft Visual Studio. 

Answer 1

[MathWorks Support Team]

This issue is typically encountered if the Linux computer on which the code is being compiled has an outdated compiler. The functions "omp_init_nest_lock" and "omp_destroy_nest_lock" are implementations of "OpenMP" specifications and they should be provided by the compiler. On a Linux computer, installing the recommended version of the GCC compiler should resolve this issue. 

Information about supported compilers for the current MATLAB release can be found at the following link:

https://www.mathworks.com/support/requirements/supported-compilers.html

Information about supported compilers for the previous MATLAB releases can be found at the following link:

https://www.mathworks.com/support/requirements/previous-releases.html

Note: this also addresses a similar issue on Ubuntu.

[Ryan Livingston]

https://www.mathworks.com/matlabcentral/answers/163264-matlab-coder-and-mex-file-generation-problem-on-linux#answer_159475

addresses a similar issue on Ubuntu.

Answer 2

[cui,xingxing]

If you use the CMake tool to compile, then it should link to the OpenMP library. Add the following example to CMakeLists.txt.

FIND_PACKAGE( OpenMP REQUIRED)
if(OPENMP_FOUND)
    message("OPENMP FOUND")
    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${OpenMP_EXE_LINKER_FLAGS}")
endif()